Gel Filtration Studies of Sugarcane Acid Phosphatases

Abstract

Gel filtration studies were conducted with sugarcane leaf-protein preparations bearing strong phosphatase activity. The objectives were to isolate phosphatases from contaminant protein, and from one another. Sephadex, a dextran gel possessing variable sieving properties, was employed in 1.5 X 25-cm. columns packed and eluted with water or buffer. Good resolution of enzyme and protein constituents was obtained. Collecting 1-ml. fractions during a typical filtration, major phosphatase activity was gathered in fractions 8 to 10, while the mass of noncatalytic protein trailed behind in fractions 19 to 24. The filtration process also served to remove such inhibitors as molybdenum and tungsten, permitting partial reactivation of inhibited enzyme. Attempts to separate phosphatases from one another by gel filtration and paper electrophoresis were negative. It was concluded that sugarcane leaf phosphatases have nearly identical properties with regard to solubility, molecular size and type of charge. A powerful protein-protein binding is also suspected among different phosphatases.